Hydrostatic non-contact seal with offset outer ring

ABSTRACT

A non-contact seal assembly includes a plurality of seal shoes arranged about a centerline in an annular array, the seal shoes including a first seal shoe extending axially along the centerline between a first shoe end and a second shoe end. The non-contact seal assembly may comprise a seal base circumscribing axially offset from the annular array of the seal shoes. The non-contact seal assembly may further comprise a plurality of spring elements, each of the spring elements radially distal from and connecting to a respective one of the seal shoes, and each of the plurality of spring elements is axially adjacent to the seal base.

This invention was made with government support under Contract No.FA8626-16-C-2139 awarded by the United States Air Force. The governmentmay have certain rights in the invention.

BACKGROUND OF THE INVENTION 1. Technical Field

The present disclosure relates generally to hydrostatic non-contactseals. More particularly, the disclosure relates to hydrostaticnon-contact seals that use an offset outer ring.

2. Background Information

Rotational equipment typically includes one or more seal assemblies forsealing gaps between rotors and stators. A typical seal assemblyincludes a contact seal with a seal element such as a knife edge sealthat engages a seal land. The hydrostatic non-contact seal includes afull ring portion that connects beams and shoes together, in order tofunction properly as a full seal ring. The full ring is located outboardof the beams and the shoes. This adds radial weight to the sealassembly. It is typical to be radially challenged for space in a gasturbine engine which may require parts to be thinned or reconfigured tofit and function properly in the design space.

It would be desirable to reduce the radial height and/or the weight ofthe seal.

SUMMARY OF THE DISCLOSURE

The following presents a simplified summary in order to provide a basicunderstanding of some aspects of the disclosure. The summary is not anextensive overview of the disclosure. It is neither intended to identifykey or critical elements of the disclosure nor to delineate the scope ofthe disclosure. The following summary merely presents some concepts ofthe disclosure in a simplified form as a prelude to the descriptionbelow.

Aspects of the disclosure are directed to a non-contact seal assembly,having a plurality of seal shoes arranged about a centerline in anannular array, the seal shoes including a first seal shoe extendingaxially along the centerline between a first shoe end and a second shoeend. The non-contact seal assembly may comprise a seal basecircumscribing axially offset from the annular array of the seal shoes.The non-contact seal assembly may further comprise a plurality of springelements, each of the spring elements radially distal from andconnecting to a respective one of the seal shoes, and each of theplurality of spring elements is axially adjacent to the seal base.

The seal base may be connected to a seal carrier surface that issubstantially cylindrical and extends circumferentially around and facestowards the centerline.

The non-contact seal assembly may further comprise a first ringstructure configured and arranged to at least one of position, supportor mount to a secondary seal device axially separated from the seal baseand radially adjacent to the first seal shoe

The non-contact seal assembly may further comprise a secondary sealdevice axially and radially adjacent to the seal base and axiallyadjacent to first the seal shoe.

The seal assembly may comprise nickel alloy.

The seal assembly may comprise one of cobalt alloy or aluminum.

The first seal shoe may extend circumferentially, at the first shoe end,between a first shoe side and a second shoe side for a seal shoe length.

The seal shoes may collectively form a substantially annular end surfaceat the second shoe end.

According to another aspect of the present disclosure, a non-contactseal is provided. The non-contact seal assembly may provide a pluralityof seal shoes arranged about a centerline in an annular array, the sealshoes including a first seal shoe extending axially along the centerlinebetween a first shoe end and a second shoe end. The non-contact sealassembly may comprise a seal base circumscribing axially offset alongthe centerline from the annular array of the seal shoes. The non-contactseal assembly may further comprise a plurality of spring elements, eachof the spring elements radially between and connecting a respective oneof the seal shoes with the seal base. The non-contact seal assembly mayfurther comprise a plurality of spring elements, each of the springelements radially distal from and connecting to a respective one of theseal shoes, and each of the plurality of spring elements is axiallyadjacent to the seal base, where a void is formed by a most radiallydistal one of the plurality of spring elements, the axially offset sealbase, a stator structure, and a ring structure that is axially separatedfrom the axially offset seal base by the plurality of spring elements.

The axially offset seal base may be connected to a seal carrier surfacethat is substantially cylindrical and extends circumferentially aroundand faces toward the centerline.

The non-contact seal assembly may further comprise a first ringstructure configured and arranged to at least one position, support ormount to a secondary seal device axially separated from the axiallyoffset seal base and radially adjacent to the first seal shoe.

The non-contact seal assembly may further comprise a secondary sealdevice that is axially and radially adjacent to the axially offset sealbase and axially adjacent to the first seal shoe.

The seal assembly may comprise nickel alloy.

The seal assembly may comprise one of cobalt alloy or aluminum.

The first seal shoe extends circumferentially, at the first shoe end,between a first shoe side and a second shoe side for a seal shoe length.

According to another aspect of the present disclosure, an assembly forrotational equipment with an axial centerline is provided. The assemblymay comprise a stator structure and a rotor structure. The assembly maycomprise a seal assembly configured to substantially seal an annular gapbetween the stator structure and the rotor structure, the seal assemblycomprising a hydrostatic non-contact seal device including a pluralityof seal shoes, an axially offset seal base and a plurality of springelements. The seal shoes arranged about a centerline in an annulararray, the seal shoes sealingly engaging the rotor structure andincluding a first seal shoe extending axially along the centerlinebetween a first shoe end and a second shoe end. The axially offset sealbase circumscribing the annular array of the seal shoes, the axiallyoffset seal base mounted with the stator structure. The assembly maycomprise a plurality of spring elements, each of the spring elementsradially distal from and connecting to a respective one of the sealshoes, and each of the plurality of spring elements is axially adjacentto the axially offset seal base, where the axially offset seal base isaxially offset with respect to the plurality of spring elements.

The axially offset seal base may be connected to a seal carrier surfacethat is substantially cylindrical and extends circumferentially aroundand faces towards the centerline.

The assembly for rotational equipment may further comprise a first ringstructure configured and arranged to at least one of position, supportor mount to a secondary seal device axially separated from the axiallyoffset seal base and radially adjacent to the first seal shoe.

The assembly for rotational equipment may further comprise a secondaryseal device that is axially and radially adjacent to the axially offsetseal base and axially adjacent to the first seal shoe.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is illustrated by way of example and not limitedin the accompanying figures in which like reference numerals indicatesimilar elements. The drawing figures are not necessarily drawn to scaleunless specifically indicated otherwise.

FIG. 1 is a top half side sectional illustration of an assembly forrotational equipment, such as for example a gas turbine engine.

FIG. 2 is a simplified isometric illustration of a portion of a primaryseal device with an axially offset outer ring for the assembly of FIG.1.

FIG. 3 is an illustration of a hydrostatic non-contact seal with anaxially offset outer ring.

FIG. 4 is a side cutaway illustration of a gas turbine engine.

DETAILED DESCRIPTION

It is noted that various connections are set forth between elements inthe following description and in the drawings (the contents of which areincorporated in this specification by way of reference). It is notedthat these connections are general and, unless specified otherwise, maybe direct or indirect and that this specification is not intended to belimiting in this respect. A coupling between two or more entities mayrefer to a direct connection or an indirect connection. An indirectconnection may incorporate one or more intervening entities or aspace/gap between the entities that are being coupled to one another.

Aspects of the disclosure may be applied in connection with a gasturbine engine.

FIG. 1 illustrates an assembly 20 for rotational equipment with an axialcenterline 22. An example of such rotational equipment is a gas turbineengine for an aircraft propulsion system, an exemplary embodiment ofwhich is described below in further detail. However, the assembly 20 ofthe present disclosure is not limited to such an aircraft or gas turbineengine application. The assembly 20, for example, may alternatively beconfigured with rotational equipment such as an industrial gas turbineengine, a wind turbine, a water turbine, or any other apparatus in whicha seal is provided between a stator structure and a rotor structure.

The assembly 20 of FIG. 1 includes a stator structure 24, a rotorstructure 26 and a seal assembly 28. This seal assembly 28 is mountedwith the stator structure 24, and configured to substantially seal anannular gap 30 between the stator structure 24 and the rotor structure26 as described below in further detail.

The stator structure 24 includes a seal carrier 32. This seal carrier 32may be a discrete, unitary annular body. Alternatively, the seal carrier32 may be configured with another component/portion of the statorstructure 24. The seal carrier 32 has an inner radial seal carriersurface 34. This seal carrier surface 34 may be substantiallycylindrical, and extends circumferentially around and faces towards theaxial centerline 22. The seal carrier surface 34 at least partiallyforms a bore in the stator structure 24. This bore is sized to receivethe seal assembly 28, which may be fixedly attached to the seal carrier32 by, for example, a press fit connection between the seal assembly 28and the seal carrier surface 34.

The rotor structure 26 includes a seal land 36. This seal land 36 may bea discrete, unitary annular body. Alternatively, the seal land 36 may beconfigured with another component/portion of the rotor structure 26. Theseal land 36 has an outer radial seal land surface 38. This seal landsurface 38 may be substantially cylindrical, and extendscircumferentially around and faces away from the axial centerline 22.The seal land surface 38 is disposed to face towards and is axiallyaligned with the seal carrier surface 34. While FIG. 1 illustrates thesurfaces 34 and 38 with approximately equal axial lengths along theaxial centerline 22, the seal land surface 38 may alternatively belonger or shorter than the seal carrier surface 34 in other embodiments.

The seal assembly 28 includes a primary seal device 40 and one or moresecondary seal devices 42; e.g., 1, 2, 3 or more secondary seal devices42. The seal assembly 28 also includes one or more additional componentsfor positioning, supporting and/or mounting one or more of the sealdevices 40 and 42 with the stator structure 24. The seal assembly 28 ofFIG. 1, for example, includes a first ring structure 44 configured forpositioning, supporting and/or mounting the secondary seal devices 42relative to the primary seal device 40. This first ring structure 44 mayalso be configured for axially positioning and/or supporting a secondend surface 46 of the primary seal device 40 relative to the statorstructure 24. The seal assembly 28 of FIG. 1 also includes a second ringstructure 48 (e.g., a scalloped support ring) configured for axiallypositioning and/or supporting a first end surface 50 of the primary sealdevice 40 relative to the stator structure 24. However, the second ringstructure 48 may be omitted where, for example, the first end surface 50of the primary seal device 40 may be abutted against anothercomponent/portion of the stator structure 24 (e.g., an annular orcastellated shoulder) or otherwise axially positioned/secure with thestator structure 24.

The primary seal device 40 may be configured as an annular non-contactseal device and, more particularly, a hydrostatic non-contact sealdevice. An example of such a hydrostatic non-contact seal device is aHydrostatic Adaptive Low Leakage (“HALO™)” seal; however, the primaryseal device 40 of the present disclosure is not limited to the foregoingexemplary hydrostatic non-contact seal device.

The primary seal device 40 includes a plurality of seal shoes 54, aplurality of spring elements 56 and a seal base/outer ring 52 that isaxially (referring to axial centerline 22) offset from the springelements 56. The seal shoes 54 are configured as arcuate bodies arrangedcircumferentially about the axial centerline 22 in an annular array.This annular array of the seal shoes 54 extends circumferentially aroundthe axial centerline 22, thereby forming an inner bore at an innerradial side 62 of the primary seal device 40. The inner bore is sized toreceive the seal land 36, where the rotor structure 26 projects axiallythrough (or into) the inner bore formed by the seal shoes 54.

Referring to FIGS. 1-3, each of the seal shoes 54 extends radially fromthe inner radial side 62 of the primary seal device 40 to an outerradial surface 64 of that seal shoe 54. Each of the seal shoes 54extends circumferentially around the axial centerline 22 betweenopposing first and second circumferential sides 66 and 68 of that sealshoe 54.

Referring to FIG. 1, each of the seal shoes 54 extends axially along theaxial centerline 22 between a first shoe end 70 and a second shoe end72. The first shoe end 70 may be axially offset from and project axiallyaway from the first end surface 50. The second shoe end 72 may beaxially offset from and project axially away from the second end surface46. The seal shoes 54 of the present disclosure, however, are notlimited to such exemplary relationships.

Each of the seal shoes 54 may include an arcuate end surface 74generally at (e.g., on, adjacent or proximate) the second shoe end 72.In the array (see FIG. 2), these arcuate end surfaces 74 collectivelyform a generally annular (but circumferentially segmented) end surface76 configured for sealingly engaging with the secondary seal devices 42;see FIG. 1. The seal shoes 54 of the present disclosure, however, arenot limited to the foregoing exemplary configuration.

Each of the seal shoes 54 includes one or more arcuate protrusions 78,which collectively form one or more (e.g., a plurality) of axiallyspaced generally annular (e.g., circumferentially segmented) ribs. 80 atthe inner radial side 62. Distal inner radial ends 82 of one or more ofthese ribs 80 are configured to be arranged in close proximity with (butnot touch) and thereby sealingly engage the seal land surface 38 in anon-contact manner (see FIG. 1), where the rotor structure 26 projectaxially through (or into) the inner bore formed by the seal shoes 54.The ribs 80 therefore are configured, generally speaking, as non-contactknife edge seal elements.

Referring to FIGS. 1-3, the spring elements 56 are arrangedcircumferentially about the axial centerline 22 in an annular array. Thespring elements 56 are also arranged radially between the seal shoes 54and the seal base 52. The spring element 56, for example, includes oneor more mounts 83 and 84 (e.g., generally radial fingers/projections)and one or more beams 86 (e.g., cantilever-leaf springs). The firstmount 83 is connected to a respective one of the seal shoes 54 at (e.g.,on, adjacent or proximate) the first circumferential side 68, where theopposing second circumferential side 66 of that seal shoe 54 is freefloating. The second mount 84 is connected to an offset seal base/outerring 52, and is generally circumferentially aligned with or near thesecond circumferential side 68. With respect to the axial center line22, the offset seal base 52 is axially offset with respect to theradially most distal beam 86, such that the offset seal base 52 does notradially cover the radially most distal beam 86. The beams are radiallystacked and spaced apart with one another. Each of these beams 86extends laterally (e.g., tangentially or circumferentially) from thefirst mount 83 to the second mount 84. These spring elements 56 maythereby laterally overlap a major circumferential portion (e.g.,˜50-100%) of the seal shoe 54. In contrast, the offset seal base 52 doesnot laterally overlap at least a primary circumferential portion (e.g.,˜65-100%) of the radially most distal beam 86. Subsequently, the radialheight of seal assembly 28 may be substantially reduced, to increaseradial space and improve packaging with adjacent hardware. FIGS. 1-3illustrate an embodiment in which the offset seal base/outer ring doesnot overlap any portion of the radially most distal of the beams 86. Thespring elements 56 of the present disclosure, however, are not limitedto the foregoing exemplary configuration or values.

During operation of the primary seal device 40, rotation of the rotorstructure 26 may develop aerodynamic forces and apply a fluid pressureto the seal shoes 54 causing the each seal shoe 54 to respectively moveradially relative to the seal land surface 38. The fluid velocity mayincrease as a gap between the seal shoe 54 and seal land surface 38increases, thus reducing pressure in the gap and drawing the seal shoe54 radially inwardly toward the seal land surface 38. As the gap closes,the velocity may decrease and the pressure may increase within the gap,thus, forcing the seal shoe 54 radially outward from the seal landsurface 38. The respective spring element 56 may deflect and move withthe seal shoe 54 to create a primary seal of the gap between the sealland surface 38 and ribs 80 within predetermined design tolerances.

Referring again to FIG. 1, while the primary seal device 40 is operableto generally seal the annular gap 30 between the stator structure 24 andthe rotor structure 26 as described above, fluid (e.g., gas) may stillflow axially through passages 96 defined by radial gaps between thecomponents. 52, 54 and 56. The secondary seal devices 42 therefore areprovided to seal off these passages 96 and, thereby, further and morecompletely seal the annular gap 30.

Each of the secondary seal devices 42 may be configured as a ring sealelement such as, but not limited to, a split ring. Alternatively, one ormore of the secondary seal devices 42 may be configured as a full hoopbody ring, an annular brush seal or any other suitable ring-type seal.

As described above, the assembly 20 of the present disclosure may beconfigured with various different types and configurations of rotationalequipment. FIG. 4 illustrates one such type and configuration of therotational equipment—a geared turbofan gas turbine engine 106. Such aturbine engine 106 includes various stator structures (e.g., bearingsupports, hubs, cases, etc.) as well as various rotor structures (e.g.,rotor disks, shafts, etc.) as described below, where the statorstructure 24 and the rotor structure 26 can respectively be configuredas anyone of the foregoing structures in the turbine engine 106 of FIG.4, or other structures not mentioned herein. Referring again to FIG. 1,while the primary seal device 40 is operable to generally seal theannular gap 30 between the stator structure 24 and the rotor structure26 as described above, fluid (e.g., gas) may still flow axially throughpassages 96 defined by radial gaps between the components 52, 54 and 56.The secondary seal devices 42 therefore are provided to seal off thesepassages 96 and, thereby, further and more completely seal the annulargap 30.

The secondary seal devices 42 of FIG. 1 are arranged together in anaxial stack. In this stack, each of the secondary seal devices 42axially engages (e.g., contacts) another adjacent one of the secondaryseal devices 42. The stack of the secondary seal devices 42 is arrangedwith the first ring structure 44, which positions and mounts thesecondary seal devices 42 with the stator structure 24 adjacent theprimary seal device 40. In this arrangement, the stack of the secondaryseal devices 42 is operable to axially engage and form a seal betweenthe end surface 76 of the array of the seal shoes 54 and an annularsurface 98 of the first ring structure 44. These surfaces 76 and 98 areaxially aligned with one another, which enables the stack of thesecondary seal devices 42 to slide radially against, but maintainsealing engagement with, the end surface 76 as the seal shoes 54 moveradially relative to the seal land surface 38 as described above.

The first ring structure 44 may include a secondary seal device supportring 100 and a retention ring 102. The support ring 100 is configuredwith an annular full hoop body, which extends circumferentially aroundthe axially centerline 22. The support ring 100 includes the annularsurface 98, and is disposed axially adjacent and engaged with the sealbase 52.

The retention ring 102 is configured with an annular full hoop body,which extends circumferentially around the axially centerline 22. Theretention ring 102 is disposed axially adjacent and engaged with thesupport ring 100, thereby capturing the stack of the secondary sealdevices 42 within an annular channel formed between the rings 100 and102. The stack of the secondary seal devices 42 may also oralternatively be attached to one of the rings 100 and 102 by, forexample, a press fit connection and/or otherwise.

Referring still to FIG. 4, the turbine engine 106 extends along an axialcenterline 108 (e.g., the centerline 22) between an upstream airflowinlet 110 and a downstream airflow exhaust 112. The turbine engine 106includes a fan section 114, a compressor section 115, a combustorsection 116 and a turbine section 117. The compressor section 115includes a low pressure compressor (LPC) section 115A and a highpressure compressor (HPC) section 115B. The turbine section 117 includesa high pressure turbine (HPT) section 117A and a low pressure turbine(LPT) section 117B.

The engine sections 114-117 are arranged sequentially along thecenterline 108 within an engine housing 118, a portion or component ofwhich may include or be connected to the stator structure 24. Thishousing 118 includes an inner case 120 (e.g., a core case) and an outercase 122 (e.g., a fan case). The inner case 120 may house one or more ofthe engine sections; e.g., an engine core. The outer case 122 may houseat least the fan section 114.

Each of the engine sections 114, 115A, 115B, 117A and 117B includes arespective rotor 124-128. Each of these rotors 124-128 includes aplurality of rotor blades arranged circumferentially around andconnected to one or more respective rotor disks. The rotor blades, forexample, may be formed integral with or mechanically fastened, welded,brazed, adhered and/or otherwise attached to the respective rotordisk(s).

The fan rotor 124 is connected to a gear train 130, for example, througha fan shaft 132. The gear train 130 and the LPC rotor 125 are connectedto and driven by the LPT rotor 128 through a low speed shaft 133. TheHPC rotor 126 is connected to and driven by the HPT rotor 127 through ahigh speed shaft 134. The shafts 132-134 are rotatably supported by aplurality of bearings 136; e.g., rolling element and/or thrust bearings.Each of these bearings 136 is connected to the engine housing 118 by atleast one stationary structure such as, for example, an annular supportstrut.

During operation, air enters the turbine engine 106 through the airflowinlet 110. This air is directed through the fan section 114 and into acore gas path 138 and a bypass gas path 140. The core gas path 138 flowssequentially through the engine sections 115-117. The bypass gas path140 flows away from the fan section 114 through a bypass duct, whichcircumscribes and bypasses the engine core. The air within the core gaspath 138 may be referred to as “core air”. The air within the bypass gaspath 140 may be referred to as “bypass air”.

The core air is compressed by the compressor rotors 125 and 126 anddirected into a combustion chamber 142 of a combustor in the combustorsection 116. Fuel is injected into the combustion chamber 142 and mixedwith the compressed core air to provide a fuel-air mixture. This fuelair mixture is ignited and combustion products thereof flow through andsequentially cause the turbine rotors 127 and 128 to rotate. Therotation of the turbine rotors 127 and 128 respectively drive rotationof the compressor rotors 126 and 125 and, thus, compression of the airreceived from a core airflow inlet. The rotation of the turbine rotor128 also drives rotation of the fan rotor 124, which propels bypass airthrough and out of the bypass gas path 140. The propulsion of the bypassair may account for a majority of thrust generated by the turbine engine106, e.g., more than seventy-five percent (75%) of engine thrust. Theturbine engine 106 of the present disclosure, however, is not limited tothe foregoing exemplary thrust ratio.

The assembly 20 may be included in various aircraft and industrialturbine engines other than the one described above as well as in othertypes of rotational equipment; e.g., wind turbines, water turbines,rotary engines, etc. The assembly 20, for example, may be included in ageared turbine engine where a gear train connects one or more shafts toone or more rotors in a fan section, a compressor section and/or anyother engine section. Alternatively, the assembly 20 may be included ina turbine engine configured without a gear train. The assembly 20 may beincluded in a geared or non-geared turbine engine configured with asingle spool, with two spools (e.g., see FIG. 5), or with more than twospools. The turbine engine may be configured as a turbofan engine, aturbojet engine, a propfan engine, a pusher fan engine or any other typeof turbine engine. The present invention therefore is not limited to anyparticular types or configurations of turbine engines or rotationalequipment.

While various embodiments of the present invention have been disclosed,it will be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible within the scope of theinvention. For example, the embodiments of the present invention asdescribed herein include several aspects and embodiments that includeparticular features. Although these features may be describedindividually, it is within the scope of the embodiments of the presentinvention that some or all of these features may be combined with anyone of the aspects and remain within the scope of the invention.Accordingly, the present invention is not to be restricted except inlight of the attached claims and their equivalents.

1. A non-contact seal assembly, comprising: a plurality of seal shoesarranged about a centerline in an annular array, the seal shoesincluding a first seal shoe extending axially along the centerlinebetween a first shoe end and a second shoe end; a seal basecircumscribing axially offset from the annular array of the seal shoes;and a plurality of spring elements, each of the spring elements radiallydistal from and connecting to a respective one of the seal shoes, andeach of the plurality of spring elements is axially adjacent to the sealbase.
 2. The non-contact seal assembly of claim 1, where the seal baseis connected to a seal carrier surface that is substantially cylindricaland extends circumferentially around and faces towards the centerline.3. The non-contact seal assembly of claim 1, further comprising a firstring structure configured and arranged to at least one of position,support or mount to a secondary seal device axially separated from theseal base and radially adjacent to the first seal shoe
 4. Thenon-contact seal assembly of claim 1, further comprising a secondaryseal device axially and radially adjacent to the seal base and axiallyadjacent to first the seal shoe.
 5. The non-contact seal assembly ofclaim 1, where the seal assembly comprises nickel alloy.
 6. Thenon-contact assembly of claim 1, where the seal assembly comprises oneof cobalt alloy or aluminum.
 7. The non-contact seal assembly of claim1, where the first seal shoe extends circumferentially, at the firstshoe end, between a first shoe side and a second shoe side for a sealshoe length.
 8. The non-contact seal assembly of claim 1, where the sealshoes collectively form a substantially annular end surface at thesecond shoe end.
 9. A non-contact seal assembly, comprising: a pluralityof seal shoes arranged about a centerline in an annular array, the sealshoes including a first seal shoe extending axially along the centerlinebetween a first shoe end and a second shoe end; a seal basecircumscribing axially offset along the centerline from the annulararray of the seal shoes; and a plurality of spring elements, each of thespring elements radially between and connecting a respective one of theseal shoes with the seal base, where a void is formed by a most radiallydistal one of the plurality of spring elements, the axially offset sealbase, a stator structure, and a ring structure that is axially separatedfrom the axially offset seal base by the plurality of spring elements.10. The non-contact seal assembly of claim 9, where the axially offsetseal base is connected to a seal carrier surface that is substantiallycylindrical and extends circumferentially around and faces toward thecenterline.
 11. The non-contact seal assembly of claim 10, furthercomprising a first ring structure configured and arranged to at leastone position, support or mount to a secondary seal device axiallyseparated from the axially offset seal base and radially adjacent to thefirst seal shoe.
 12. The non-contact seal assembly of claim 10, furthercomprising a secondary seal device that is axially and radially adjacentto the axially offset seal base and axially adjacent to the first sealshoe.
 13. The non-contact assembly of claim 12, where the seal assemblycomprises nickel alloy.
 14. The non-contact assembly of claim 12, wherethe seal assembly comprises one of cobalt alloy or aluminum.
 15. Thenon-contact assembly of claim 1, where the first seal shoe extendscircumferentially, at the first shoe end, between a first shoe side anda second shoe side for a seal shoe length.
 16. An assembly forrotational equipment with an axial centerline, the assembly comprising:a stator structure; a rotor structure; and a seal assembly configured tosubstantially seal an annular gap between the stator structure and therotor structure, the seal assembly comprising a hydrostatic non-contactseal device including a plurality of seal shoes, an axially offset sealbase and a plurality of spring elements; the seal shoes arranged about acenterline in an annular array, the seal shoes sealingly engaging therotor structure and including a first seal shoe extending axially alongthe centerline between a first shoe end and a second shoe end; theaxially offset seal base circumscribing the annular array of the sealshoes, the axially offset seal base mounted with the stator structure;and a plurality of spring elements, each of the spring elements radiallydistal from and connecting to a respective one of the seal shoes, andeach of the plurality of spring elements is axially adjacent to theaxially offset seal base, where the axially offset seal base is axiallyoffset with respect to the plurality of spring elements.
 17. Theassembly for rotational equipment of claim 16, where the axially offsetseal base is connected to a seal carrier surface that is substantiallycylindrical and extends circumferentially around and faces towards thecenterline.
 18. The assembly for rotational equipment of claim 16,further comprising a first ring structure configured and arranged to atleast one of position, support or mount to a secondary seal deviceaxially separated from the axially offset seal base and radiallyadjacent to the first seal shoe.
 19. The assembly for rotationalequipment of claim 16, further comprising a secondary seal device thatis axially and radially adjacent to the axially offset seal base andaxially adjacent to the first seal shoe.